Structural elements and process of forming the same



lr Maw Unite STRUCTURAL ELEMENTS AND PROCESS OF FORNIING THE SAME No Drawing. Application March 18, 1953, Serial No. 343,232

Claims priority, application Germany March 19, 1952 7 Claims. (Cl. 106-284) The present invention relates to new structural elements and process of forming the same and more particularly to structural elements which are weather-resistant, bacteria-, insect-, and acid-resistant as well as being resistant to penetration by roots. The structural elements according to tne present invention are strong and have sound absorbing properties. These structural elements are formed from ordinary pulverulent filler type building materials and a agent of the bituminous type.

Prior processes of forming structural elements by the mixing of a pulverulent filler and a warm bituminous mass could not produce all of the above enumerated properties.

The use of bituminous substances as binding agent according to the known processes resulted in the formation of final products which show the following deficiencies:

(a) If the binding agent consisted of a natural bitumen, the molded article was not resistant to ba ct'ri'zi ifisects and penetration by roots and becam dis iiitegrated or decayed in earth.

(b) If pitch was used as binding agent then there was no guarantee as to the desired strength and elasticity of the final product.

The known processes consisted of mixing finely divided filler type building material with a hot bituminous substance and then compressing the mass. However, despite many variations in this basic process, the above enumerated deficiencies of the final product prevented extensive application of the use of such bituminous substances as binding agent in the production of structural elements.

It is therefore an object of the present invention to provide a process of forming structural elements utilizing bituminous substances as binding agents, whereby the above enumerated deficiencies of the final products are overcome.

It is a further object of the present invention to provide a simple process of forming weather-, bacteria-, and insect-resistance structural element from ordinary pulverulent fillers and bin g agents consisting of bituminous substances.

It is a still further object of the present invention to provide a process of forming structural elements which process has the advantage of facility of drying of the mass.

It is another object of the present invention to provide a process of forming structural elements which are resistant to the formation of cracks and fissures by action of heat, dryness and dampness.

Other objects of the present invention will be apparent from the further reading of the specification and the appended claims.

With the above objects in view, the present invention mainly comprises as a process of forming structural elements, comprising the steps of intimately mixing at least one pulverulent filler with an aqueous dispersion 2,738,287 Patented Mar. 13, 1956 of at least one bitumen, a water-dispersible clay and at least 0.5% by weight of the weight of the dispersion of at least one polycyclic aromatic hydrocarbon having a maximum of three rings which polycyclic hydrocarbon has been added to the dispersion so as to form a homogeneous mass thereof, and drying the thus formed homogeneous mass, thereby hardening the same into a coherent mass, thus forming a structural element.

The term pulverulent filler as used throughout the specification and claims is meant to designate the pulverulent filler type building materials such as sand, stone, sawdust, flue dust, pumice, slag sand and similar substances which in sub-divided or pulverulent form are used with binding agents in the formation of bricks, stones and other structural elements.

The polycyclic aromatic hydrocarbon utilized in the composition according to the present invention are preferably present in an amount between 1-4% by weight of the weight of the aqueous bitumen dispersion. The preferred polycyclic aromatic hydrocarbon are those obtained from the high boiling point distillation of mineral coal and the like, and includes raw naphthalene, naphthalene, raw anthracene, anthracene, raw phenanthrene, phenanthrene, and the like. It should be noted that raw naphthalene and raw anthracene may contain phenanthrene and carbazole in amounts up to about 30%. It should also be noted that individual polycyclic aromatic hydrocarbon or mixtures thereof may be used.

Certain bitumens will contain more or less amounts of the polycyclic aromatic hydrocarbon having a maximum of three rings. However, it will always be necessary according to the present invention to add such hydrocarbon in greater or lesser amounts in order that the amount by weight of the hydrocarbon in the final aqueous bitumenous dispersion be at least 0.5% and preferably between 1-4% by weight. The additional polycyclic aromatic hydrocarbon may be added either directly to the bitumen itself or to the water with which the bitumen is mixed.

Particularly in the latter event it is desirable to utilize instead of plain water a gas condensate obtained by condensation of gases from coke purification processes. The gas condensate is obtained upon cooling of the gas after removal of ammonia and particularly in a coking process wherein the desulfurized gas is freed from benzol under pressure. By escape of the gases from the desulfurizing there is obtained water-saturated gas at a temperature of about 30-35 C. which is then compressed at a pressure of about 7-9 atmospheres. The compression of the gas increases the temperature thereof to about 7585 C. The gas is thenfed at this pressure to a pressure cooler in which the gas by indirect cooling is cooled to a temperature of about 20 C., thereby obtaining a gas condensate. The gas loses the water and naphthalene contained therein until only traces remain. The gas may then be further processed and used as consumer gas. The remaining gas condensate contains up to about 0.20% naphthalene, traces of light oil, is milky and has a temperature of about 20-23 C. A gas condensate consists mainly of condensed water. It is also possible to increase the contents of polycyclic aromatic hydrocarbon in the gas condensate by the addition thereto of high boiling mineralcoal tar products such as naphthalene, anthracene, phenanthrene and the like.

The bitumen which is utilized according to the present invention may be any of the usual bitumens in the form of mineral coal tar pitch obtained by ordinary methods to which decomposed coal is added or it may be obtained by air blowing of mineral coal to produce airblown mineral coal tar pitch. A fluxing oil may be added to either of the above type mineral coal tar pitch. Although mineral coal tar pitch to whih decomposed coal is added or which is obtained by air blowing process is preferred according to the present invention, other bitumens may be utilized such as wash oil pitch, brown coal tar pitch, coke oven tar, oil gas tar, water gas tar, etc. It is also possible to use mixtures of different bitumen substances.

The bitumen utilized should preferably have a softening point which is no higher than 60 C. according to Kraemer-Sarnow, or if it has a higher softening point it should preferably be refluxed until the Kraemer-Sarnow softening point is no higher than 60 C. The Kraemen Sarnow softening point refers to the temperature at which a mercury column in a little tube having an inner diameter of 6 mm. and weighing g. passes through a tar pitch or bitumen layer of 5 mm. height which is contained in a little tube of the same inner diameter.

Any water-dispersible clay may be utilized according to the present invention and the clay is preferably of very small particle size. Examples of such water-dispersible clays include kaolin, silicic acid, etc., the present invention, however, not being limited to any specific clay.

The process generally comprises mixing a wet or wetted pulverulent filler type building material with the above defined aqueous dispersion. It is also possible to mix the finely divided building material with water or gas condensate and to add to the mixture the dispersion components except for water, namely, bitumen, clay and polycyclic aromatic hydrocarbon. It is also possible to mix the pulverulent filler with the dispersion components except for the water and to add the water to the formed mixture. In either case, the mixing is carried out so as to form a homogeneous mixture which may then be molded or shaped in the desired form and dried to form the final hardened coherent mass.

According to a preferred embodiment of the present invention the pulverulent filler instead of being mixed with the aqueous dispersion is instead mixed with molten tar pitch at a temperature up to about 100 C. The molten tar pitch consists preferably of mineral coal tar pitch and decomposed coal or air-blown mineral coal tar pitch. In either case a fluxing oil may be mixed with the mineral coal tar pitch. It is, of course, necessary, to add sufficient polycyclic aromatic hydrocarbon to the molten tar pitch so as to have the desired amount present.

As stated above, the production of the dispersion or of the molten tar pitch is carried out whereby the final applied pitch preferably has a maximum Kraemer-Sarnow softening point of 60 C. The decomposed coal may be obtained from small mineral coal, mineral coal dust, mineral coal tar and/or mixtures of mineral coal tar products which no longer distill at temperaturesmp to about 200 C.

The easy mixability of the dispersion or of the molten tar pitch, which is preferably applied in a thin stream,

with the finely divided building material is due to the low Y viscosity and the extraordinary wetting and penetrating ability, which may be further increased by the addition of water and/ or gas condensate to the building material. The wetness of the building material may be raised to about by the addition of water and/or gas condensate. After drying the final molded article has a very high strength and solidity. The tamping mass must be further worked immediately after it is formed. The amount of dispersion or molten tar pitch in order to achieve the desired properties can vary within rather wide limits and is preferably between l-30%. If tar pitch alone is utilized, it must first be heated and molten; this is not necessary, however, with the use of a dispersion.

After the molding or shaping it is necessary to take care so that no additional moisture comes in contact therewith. After drying and solidifying the final product is weather-resistant. The drying can be accelerated by guiding the molds through warm air heated chambers. Depending on the type of pulverulent filler, it is possible to subject the molded article to a burning process. By

the use of clay or mud as building material, it is possible to produce building or clinker stones.

The intimate mixing of clay, water and dispersion or molten tar pitch results in the evaporation of water on the surface of the molded article, akin to sweating. Not only is the surface water, but also the capillary water of the building material is expelled by the molten tar pitch or the dispersion so that a fine skin of tar pitch is formed around each small portion. The water is found between these portions. The surface tension of the tar pitch substance is so great that little by little the individual portions contract, whereby the water is expelled onto the surface of the molded object and is there evaporated. This procedure takes about 24 hours. During this time the water content is lowered from about 16% to about 3%. It is also possible by artificial drying, at about C. to speed up this procedure. In such case, the molded article may be dried and solidified after about 8 hours. In this way it is possible to produce building stones from clay which correspond to ordinary building blocks although the same have not yet been burned.

Although prior processes for the production of molded clay objects required drying in air for about 2-3 weeks before burning, or about 67 days in a drying chamber, according to the present invention it is possible to produce clay molds after only one to two days drying in a drying chamber, before burning. Even drying in the open air requires only 1 /2 to 2 /2 days to produce molds ready for burning.

An additional advantage of the process of the present invention, besides the extraordinarily shortened drying time, resides in the fact that the structural elements produced according to the present invention utilizing clay and eventually burning the formed brick do not crack and become brittle during the burning as in the case of clay bricks produced according to the known processes.

The present invention is advantageous therefore both in the production of burned and non-burned building stones.

An additional advantage of the present invention is obtained upon burning which results, due to the good dis tribution of the binding agent, in the formation of a coherent mass having a wet surface which thereby results in a formation of a product wherein no cracks are formed on the surface because of the sweating and evaporation of the water on the surface of the same.

Moreover, the tar pitch content of the dispersion or the molten tar pitch acts as a finely distributed combustible so that the burning advances progressively to a great extent in the oven thereby resulting in a saving of fuel.

A further advantage of the present invention resides in the fact that the clay stones may be formed in winter as well as any other time without ceasing production because drying in open air does not cause any cracks to be formed by the cold.

The following examples are given as illustrative of preferred process according to the present invention, the scope of said invention not, however, being limited to the examples given.

Example Finely divided pumice is wetted with about 10% water. To 50 kg. of this wetted pumice is added 2.5 kg. of molten air-blown mineral coal tar pitch (Kraemer-Sarnow softening point-35 C.) to which has been added 0.05 kg. raw anthracene. The resulting mass is thoroughly mixed, then molded and allowed to dry at room temperature for about 1 /2 days. The resulting product is a hard, temperatureand organism-resistant building block.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one pulverulent filler, at least one polycyclic aromatic hydrocarbon having a maximum of three rings, and an aqueous dispersion consisting essentially of water, of at least one aromatic bitumen having a maximum Kraemer-Sarnow softening point of 60 C. and of a water dispersible clay so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 0.5-4% by weight of the weight of said aqueous dispersion; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

2. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one pulverulent filler, at least one polycyclic aromatic hydrocarbon having a maximum of three rings, and an aqueous dispersion consisting essentially of water, of at least one aromatic bitumen having a maximum Kraemer-Sarnow softening point of 60 C. and of a water dispersible clay so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 14% by weight of the weight of said aqueous dispersion, and the amount of said aqueous dispersion being between 130% of said mixture; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

3. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one pulverulent filler, at least one polycyclic aromatic hydrocarbon having a maximum of three rings and being selected from the group consisting of naphthalene, anthracene and phenanthrene, and an aqueous dispersion consisting essentially of water, of at least one aromatic bitumen having a maximum Kraemer-Sarnow softening point of 60 C. and of a water dispersible clay so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 0.5-4% by weight of the weight of said aqueous dispersion; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

4. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one pulverulent filler, at least one polycyclic aromatic hydrocarbon having a maximum of three rings, and an aqueous dispersion consisting essentially of water, of at least one aromatic bitumen consisting of mineral coal tar pitch and decomposed coal and having a maximum Kraemer-Sarnow softening point of 60 C. and of a water dispersible clay so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 0.5-4% by weight of the weight of said aqueous dispersion; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

5. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one pulverulent filler, at least one polycyclic aromatic hydrocarbon having a maximum of three rings, and an aqueous dispersion consisting essentially of water, of at least one aromatic bitumen consisting of air-blown mineral coal tar pitch having a maximum Kraemer-Sarnow softening point of 60 C. and of a water dispersible clay so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 0.54% by weight of the weight of said aqueous dispersion; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

6. A process of forming structural elements, comprising the steps of adding to each other in any desired sequence and intimately mixing at least one polycyclic aromatic hydrocarbon having a maximum of three rings, at least one pulverulent filler, and at least one molten aromatic bitumen having a maximum Kraemer-Sarnow softening point of 60 C. so as to form a mixture thereof; adding Water and a water dispersible clay to the thus formed mixture so as to form a homogeneous mixture thereof, the amount of said added polycyclic hydrocarbon being such that the amount of polycyclic hydrocarbon in the thus formed mixture is between 0.54% by weight of the weight of said bitumen, said water and said water dispersible clay; and drying the thus formed homogeneous mixture, thereby hardening the same into a coherent mass and thus forming a structural element.

7. A shaped structural element, comprising an intimately mixed hardened coherent mass of finely divided pumice, air-blown mineral coal tar pitch having a Kraemer-Sarnow softening point of about 35 C., and anthracene in a ratio of about 50 parts by weight of said pumice to 2.5 parts by weight of said mineral coal tar pitch to 0.05 part by weight of said anthracene.

References Cited in the file of this patent UNITED STATES PATENTS 74,963 White Feb. 25, 1868 1,240,253 Popkess Sept. 18, 1917 1,440,355 Morrell Dec. 26, 1922 1,781,105 Dounard Nov. 11, 1930 1,988,543 Daimler Jan. 22, 1935 2,332,933 Roediger Oct. 26, 1943 2,521,783 Farber Sept. 12, 1950 FOREIGN PATENTS 216,911 Great Britain June 5, 1924 244,561 Great Britain Dec. 24, 1925 441,879 Great Britain Jan. 27, 1936 20,781 Australia of 1935 23,881 Australia of 1935 112,032 Australia Dec. 12, 1940 

1. A PROCESS OF FORMING STRUCTURAL ELEMENTS, COMPRISING THE STEPS OF ADDING TO EACH OTHER IN ANY DESIRED SEQUENCE AND INTIMATELY MIXING AT LEAST ONE PULVERULENT FILLER, AT LEAST ONE POLYCYCLIC AROMATIC HYDROCARBON HAVING A MAXIMUM OF THREE RINGS, AND AN AQUEOUS DISPERSION CONSISTING ESSENTIALLY OF WATER, OF AT LEAST ON AROMATIC BITUMEN HAVING A MAXIMUM KRAEMER-SARNOW SOFTENING POINT OF 60* C. AND OF A WATER DISPERSIBLE CLAY SO AS TO FORM A HOMOGENEOUS MIXTURE THEREOF, THE AMOUNT OF SAID ADDED POLYCYCLIC HYDROCARBON BEING SUCH THAT THE AMOUNT OF POLYCYCLIC HYDROCARBON IN THE THUS FORMED MIXTURE IS BETWEEN 0.5-4% BY WEIGHT OF THE WEIGHT OF SAID AQUEOUS DISPERSION; AND DRYING THE THUS FORMED HOMOGENEOUS MIXTURE, THEREBY HARDENING THE SAME INTO A COHERENT MASS AND THUS FORMING A STRUCTURAL ELEMENT. 